光敏交联型聚酰亚胺气凝胶纤维的制备

聚酰亚胺气凝胶材料以其质轻、强度高及耐热性好等特点，在航空航天、隔热防护、催化剂载体等领域具有广泛的应用前景，而可弯曲、可编织的柔性气凝胶纤维无疑在精密复杂结构、可穿戴等领域具有更明显的优势。为此，本项目拟设计合成主链或者侧链含光敏基团的线性高分子量的聚酰亚胺纺丝液，采用冻胶纺丝方法使纤维成形，同时通过紫外辐射使聚酰亚胺分子链发生光交联反应，制得聚酰亚胺湿凝胶纤维，再经溶剂交换、冷冻干燥制备出交联型聚酰亚胺气凝胶纤维。在冻胶纺丝过程中进行大分子交联反应，解决了聚合物溶液的可纺性与气凝胶所需的三维交联结构之间的矛盾，同时交联结构可降低产物的体积收缩率、提升纤维的力学性能。构建光敏基团、聚合物溶液可纺性、湿凝胶纤维微结构以及气凝胶纤维形态结构的相互关系，发展一种通过冻胶纺丝技术制备聚酰亚胺气凝胶纤维的方法，为该类材料规模化制备提供理论依据和技术支撑。

Polyimide aerogels have the extensive potential in numerous applications including aerospace, thermal insulation, and catalysis supporter due to their light weight, high strength and heat resistance. Furthermore, foldable and woven flexible aerogel fibers undoubtedly have obvious advantages as the sophisticated structures and wearable materials. Here, this project intends to design a production process for polyimide aerogel fibers starting from a linear high-molecular-weight polymer solution containing photosensitive groups located either in the polymer backbone (main chain) or a side chain. The fibers are fabricated by a gel spinning method, whereby the polyimide fibers are then subsequently irradiated by ultraviolet light. The photo-crosslinking reaction occurs between the polymer chains to obtain polyimide wet-gel fibers, which then undergo consecutive solvent exchange and freeze-drying to form polyimide aerogel fibers. To overcome the contradiction between the spinnability of the polymer solution and the 3D crosslinked structure of aerogel networks, the gel spinning of the fibers is synchronized with the crosslinking reaction. Moreover, the crosslinked structure can reduce the shrinkage of aerogel fibers and enhance the mechanical properties. We want to establish relationship among the incorporation of photosensitive groups, the spinnability of the polymer solution, the microstructure of the wet-gel fibers, and the morphology and structure of the resulting aerogel fiber, and thus to develop a method to fabricating polyimide aerogel fibers from the gel-spinning. This technique provides a theoretical basis and technical support for large-scale preparation of similar aerogel fiber.